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Formulating cold tone paper developers

Thiourea is banned in some states in the US. Interestingly enough in some of those states, it is found as a natural product in many common wildflowers. The toxicity of thiourea has been under debate for quite a while and nothing seems to be done. I think that it is due to the fact that the results are not conclusive enough.

PE
 
And it's been traditionally used in silver polish too. That said, chemical safety sources list it as a possible carcinogen.
 

Unfortunately I have no access to a Densitometer, there's never been a tradition of photographers using them in the UK, outside professional colour labs.

The shift we are looking for is past Neutral to a Blue black tone, Thiourea appears to be capable of doing this but there are organic alternatives.

The work on Thiourea to give blue/black tones was by a British Photo-chemist C.E.K. Mees of Wratten & Wainwright, Kodak bought the company and he moved to the US to set up Kodak's Rochester Resarch Laboratories.

Ian
 
Ian - If you want to send me some samples/step wedges, I'll read them and post results. Then we can compare with my modified Ansco 130 developer. PM me and I'll give you my address.

By the way, I don't know why more people don't use color densitomety so they can better discuss these matters...
 
Densitometry is useless unless it is comparative densitometry with a check and the experiment!

PE
 
That's what I plan on!
 
Phenyl Mercaptotetrazol in about 5-10 mg / l conc. of PQ gives a definite bluer tint than benzotriazole. It also makes the blacks a bit deper. I found out, that Forte Fortezo reacted with pepper grain with amounts over 8 mg/l conc. Nitrobenzimidazole is another agent, that makes the tone bluer.
I bought my Phenylmercaptotetrazol at Organica in Wolfen, Germany.

Best regards
Gerhard
 
The Photographers Formulary had 1-phenyl-5-mercaptotetrazol last year. A percent solution, 100 ml bottle is what I bought. It was pretty inexpensive. I suspect they still have it. Email them and ask, as I can't find it on the web site.
 
I have mixed up a developer containing Potassium Iodide instead of Benzotriazole and will report back.

Metol 4g, Sodium Sulphite 25g, Hydroquinone 12g, Sodium Carbonate 65g, Potassium Iodide 16g, water to make 1000ml.

I intend to dilute 1+3 for the working solution to get in the middle of the Potassium Iodide content range suggested by Ian Grant.


Tom.
 
Last edited by a moderator:
Initial impressions of Potassium Iodide

Photo Engineer said:
KI at that level is going to be interesting to hear about. Please keep us posted.

PE
Click to expand...

PE,

Your statement was well chosen. At the dilution used (4g KI per litre of working solution) only a faint image appeared on ILFORD Galerie and no image on Slavich Unibrom.

Switching to Kentmere Bromide: Mixing up a fresh developer with no restrainer and then adding 50ml of the initial KI containing developer did seem to produce a blue "tone" along with extensive yellow staining. However, after approximately four minutes in the fixer, both the blue "tone" and the yellow stain had vanished. Tonality and density on the final print(s) are fine but there is little evidence of attempts to produce cold tones.

The addition of a further 100ml of the KI containing developer to the working solution significantly retarded development and produced a mottling effect.

Tom.
 
KI should be used sparingly in the developer with paper emulsions. They can "tone" the image, but will retard development significantly. Toning in this sense, to make warm toned papers, is best done in the emulsion making process or by adding toning pigments to the paper support or both.

PE
 

I forgot to add, that the Phenyl Mercapto Tetrazole solution has a concentration of 1g in 1 liter of destilled water with a pinch of soda (0,8g) for better solubility.
 
Phenyl Mercaptotetrazol sounds like it does what people have said thiocyanates will do
I in my own goofy way added some pot. thiocyanate to 103 and got quite purplish blue tones but also lower contrast
maybe just too much
probably needs measured in grains per liter
 
PMT and Thiocyanate are at the opposite end of the spectrum in terms of what they do. PMT forms a more insoluable silver salt and gives you less speed and development, but SCN forms a more soluable salt giving solvation effects, and lower contrast. They both change tone. Their useful range in developers are vastly different, PMT being used in the mg range and SCN being used in the gram range.

PE
 
In reference to the discontinued Harman Cooltone product, I take it the presence of a proprietary restrainer would lend the greatest influence in producing blue-black tones even on papers such as Kentmere Kentona?

Tom.
 
Tom;

Generally, the toning agent in the emulsion formula will overwhelm (or tend to overwhelm) any effects of tone adjustment possible by the addenda in the developer. The first word in the previous sentence is most important! It is difficult to predict, not knowing the formula.

Sometimes, just the method of precipitation will significantly alter an emulsion formula all else being equal. I have seen a formula in which everything is the same except for the order of addition, but that order changes the tone of the image with no change in developer or addenda.

PE
 
Harman Cooltone was really something! After Mike Crawfords article in BW Photography I tried the new Harman Warm- and Cooltone developers, I was delighted! These two, and in combination, and together with Ilford MG Warmtone and Forte Polywarmtone was excellent and quite enough for me - need nothing more!! But the very best things in may years: Harman Cooltone and Polywarmtone sadly disappeared.
Now the POLYWARMTONE PROJECT has started !!! (http://www.polywarmton.com/English/register.php), time to start the HARMAN COOLTONE PROJECT??? (-- at least a working formula!)
//Bertil
 
cooltones


I think John is right, if your paper has a warmer base you will be fighting a losing battle. I use EDU. Ultra(foma) paper which is decidely warm. Comparing the paper base to Ilford you can see it is not as white. That said I have found a way to cool it off to my liking: I develope in a coldtone developer i.e. ansco 103 or one of many similiar formulas diluted 4:1(increases exposure time)with about 10ml of 1% BZT added per liter of working solution then tone in selenium 20:1 for 4mins. This comes real close to prints with ilford MGVI but I find the foma paper has a more pleasing tonal scale TO MY EYE(caps because all things are relative). My eye is no better than anyone elses just different. Another advantage of the foma paper is that if you want really beautiful warm tones you can develop in Ethol LPD 2:1.
 
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